How to Find Your UPRN Number
The National Land and Property Gazetteer and Local Land and Property Gazetteers are the backbone of UK address data infrastructure. Here is everything local authority teams need to know — and how UPRN matching keeps your data aligned with the national standard.
What is the LLPG — Local Land and Property Gazetteer?
A Local Land and Property Gazetteer (LLPG) is a definitive, council-maintained database of every addressable property and land parcel within a local authority's boundary. Each record in an LLPG contains a Unique Property Reference Number (UPRN), the full address in a standardised format, geographic coordinates, and classification information.
LLPGs are maintained by Local Land and Property Gazetteer Custodians — council officers responsible for keeping address records current and accurate. When a new property is built, an address is changed, or a building is demolished, the LLPG custodian updates the record and the change flows upstream into the national dataset.
Every local authority in England and Wales maintains its own LLPG. These local datasets are the source of truth for address data within each council area — and the foundation of the national dataset.
What is the NLPG — National Land and Property Gazetteer?
The National Land and Property Gazetteer (NLPG) is the aggregated national dataset built from contributions by all local authority LLPGs across England and Wales. It brings together every address and land parcel record into a single, nationally consistent dataset — forming the authoritative reference for UK property data.
The NLPG is managed by GeoPlace, the joint venture between the Local Government Association and Ordnance Survey. GeoPlace assigns UPRNs, maintains the data standards that govern how addresses are captured and formatted, and publishes the data as part of the AddressBase product suite used across central government, emergency services, and commercial organisations.
LLPG
→ Maintained by individual councils
→ Covers one local authority area
→ Updated by LLPG Custodian
→ Source data for the national dataset
→ Used internally across council services
LLPG vs NLPG — Key Differences
NLPG
→ Maintained by GeoPlace
→ Covers all of England and Wales
→ Updated via LLPG contributions
→ Published as AddressBase
→ Used by government, emergency services, commercial orgs
Gazetteer Management: Keeping Your LLPG Accurate
Effective gazetteer management is one of the most important — and most underresourced — functions in local authority data teams. An LLPG that falls behind creates ripple effects across every council service that depends on address data: housing allocations, revenues and benefits, environmental services, social care, and emergency response.
The core challenge is matching address data across systems:
Data entered inconsistently
Different services capture addresses differently — housing might use "Flat 2a" while revenues records "2A Flat". Neither matches the LLPG record.
Legacy system migrations
When council systems are upgraded or replaced, historical address data often arrives in non-standard formats that don't align with current LLPG records.
New developments
New-build properties are often occupied before their UPRN is formally assigned — creating a window where address records exist but can't be matched.
Address changes
Street renamings, property renumberings, and sub-divisions create address changes that need to be reflected across all systems simultaneously.
How UPRN Matching Supports LLPG Compliance
Semilariti's UPRN matching platform helps local authority teams keep operational data aligned with their LLPG by resolving address records from any council system back to their authoritative UPRN.
Whether you are cleaning a housing register, standardising a revenues dataset, or aligning social care records ahead of a system migration, Semilariti processes your address data and returns UPRN-matched, standardised records — ready to load back into your systems.
95% Accuracy
Industry-leading match rate on real-world council address data — including legacy records and non-standard entries.
Bulk Processing
Process an entire housing register or council tax database in a single upload. Results returned in 5 to 30 minutes.
Confidence Scores
Every matched record includes a confidence score — so your team knows exactly which records to trust and which need review.
Who Is Responsible for the LLPG?
Every local authority in England and Wales has a designated LLPG Custodian — the council officer responsible for maintaining the accuracy and completeness of the local gazetteer. This is a formal role with specific responsibilities defined by GeoPlace. The LLPG Custodian manages the addition of new property records when developments are completed, updates records when addresses change, closes records when properties are demolished, and ensures the council's gazetteer data meets the quality standards required for inclusion in the national dataset. In practice, LLPG Custodians often work under significant pressure. New development activity generates a steady stream of new records to add. Address changes — street renamings, property renumberings, block reconfigurations — require careful coordination across multiple systems. The operational data coming in from housing, revenues, and other services may not always align with the gazetteer's current records. UPRN matching tools like Semilariti reduce the manual reconciliation work required when address data from different sources needs to be resolved against the authoritative LLPG.AddressBase: The Published Form of the National Dataset
The NLPG data is published commercially as AddressBase by Ordnance Survey, in partnership with GeoPlace. It is available in several products at different levels of detail. AddressBase Core covers all postal addresses in Great Britain, matched to Royal Mail's Postcode Address File, with UPRNs assigned. AddressBase Plus adds property classification, coordinates, and the relationship between postal addresses and their UPRN. AddressBase Premium is the most complete product. It includes every addressable location in Great Britain — including non-postal addresses — with full property lifecycle records, multiple address representations, and parent-child relationships between properties. Access to AddressBase Premium requires a licence from Ordnance Survey, and the licence fees are substantial for most organisations. Semilariti provides UPRN matching capability using databases derived from AddressBase, making this level of accuracy available at a significantly lower cost.Practical Implications for Council Data Teams
For data teams working within UK councils, the LLPG and NLPG are not abstract concepts. They are the reference standard that all operational address data should be measured against. When a housing officer creates a new tenancy record, the address should match the LLPG. When revenues and benefits processes a new claim, the address should match the LLPG. When planning logs a new application, the address should match the LLPG. In practice, it often does not. Addresses are entered quickly, sometimes from memory or from documents that contain inconsistencies. The result is operational data that sits slightly out of alignment with the authoritative source — not wrong enough to be obviously incorrect, but not right enough to enable reliable automated matching. Regular UPRN matching brings this data back into alignment. Using Semilariti, councils can take a dataset from any system and return it to LLPG-aligned, UPRN-tagged records — without the cost and complexity of a full AddressBase licence or a managed data services contract.